Slowdown and Recovery of the Atlantic Meridional Overturning Circulation and a Persistent North Atlantic Warming Hole Induced by Arctic Sea Ice Decline
Slowdown and Recovery of the Atlantic Meridional Overturning Circulation and a Persistent North Atlantic Warming Hole Induced by Arctic Sea Ice Decline
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DOI：
10.1029/2022gl097967
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发表时间：
2022-08-28
影响因子：
5.2
通讯作者：
Guilyardi, Eric
中科院分区：
文献类型：
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作者：
Ferster, Brady S.;Simon, Amelie;Guilyardi, Eric
我们在耦合大气环流模型（IPSL-CM5A2）扰动实验中研究了北极海冰损失对大西洋经向翻转环流（AMOC）和北大西洋气候的影响，其中北极海冰减少直至达到无冰夏季的平衡。几十年后，我们观察到由于地表水变暖导致冰岛盆地稠水形成减少而导致 AMOC 减弱，后来又通过西副极地北大西洋稠水形成的加剧而得到补偿。因此，AMOC 在深而稠密的水域中略有减弱，但通过较浅、密度较小的水域的翻转而恢复。与此同时，风驱动的强化和副极地环流向东南扩展导致了类似于北大西洋“暖洞”的深度延伸冷异常，类似于北纬 50 度左右 2 摄氏度。我们得出的结论是，补偿性稠密水层会在海冰消退后驱动 AMOC 变化，并且变暖洞可以独立于 AMOC 调节而发展。
We investigate the impact of Arctic sea ice loss on the Atlantic meridional overturning circulation (AMOC) and North Atlantic climate in a coupled general circulation model (IPSL-CM5A2) perturbation experiment, wherein Arctic sea ice is reduced until reaching an equilibrium of an ice-free summer. After several decades we observe AMOC weakening caused by reduced dense water formation in the Iceland basin due to the warming of surface waters, and later compensated by intensification of dense water formation in the Western Subpolar North Atlantic. Consequently, AMOC slightly weakens in deep, dense waters but recovers through shallower, less dense waters overturning. In parallel, wind-driven intensification and southeastward expansion of the subpolar gyre cause a depth-extended cold anomaly similar to 2 degrees C around 50 degrees N that resembles the North Atlantic "warming hole." We conclude that compensating dense water formations drive AMOC changes following sea ice retreat and that a warming hole can develop independently of the AMOC modulation.